The present invention relates to an automotive electric lock, and more particularly to a high-thrust clutch-type automotive electric lock with which sufficient torque is output while no counter electromotive force will be produced to form a resistance during unlocking the lock with a key.
It is known that most conventional automotive electric locks are driven directly through gears. That is, a torque output by a motor rotating at high speed is amplified through a high gear ratio to reduce the turns of rotation of a reduction gear. The reduction gear directly moves a push rod that in turn moves an external mechanical door lock connecting rod to an open or close position, so as to unlock or lock the electric door lock. To increase the torque, it is a common way to increase the gear ratio. As a result, a counter electromotive force is generated when the motor rotates. The larger the gear ratio is, the bigger the counter electromotive force is. When a key is used to unlock or lock a door, it might be bent or broken by a resistance produced by the big counter electromotive force. FIG. 1 illustrates a conventional automotive electric lock designed to solve the problem of resistance produced by the counter electromotive force. According to the mechanical principle employed in the automotive electric lock of FIG. 1, a worm (W) guides a push block (A) to move forward or backward along it in order to pull a push rod (D). When the push rod (D) is pulled to a dead point, a front end (A') of the push block (A) pushes a corresponding push point (D') on the push rod (D) outward to reach the right side of the point (D'). At this point, the push rod (D) can be pushed leftward without any resistance. With this arrangement, some power is consumed for the point (A') to push the point (A') away and therefore results in decreased power output. Moreover, the elasticity of point (D') also results in reduced power output.